Localisation of function

Question 1

Define localisation of function

Answer 1

• Means that specific functions of the brain have specific locations in the brain.

Question 2

History of localisation of function.

Answer 2

• Before the 19th century psychologists widely adopted a holistic approach of the brain- all parts of the brain were thought to be involved in the processing of thoughts and actions.
• Broca’s and Wernicke’s areas were discovered in the late 19th century and challenged this view.
• It is now widely assumed that certain areas of the brain have particular functions.
• This means that if the brain was damaged in a specific area the associated function would also be damaged.

Question 3

How is the brain divided?

Answer 3

• The brain is divided into 2 symmetrical halves called the left and right hemispheres.
• It also contains 4 lobes: the frontal, temporal, parietal and occipital lobes.
• some functions are dominated by one hemisphere (hemispheric lateralisation).

Question 4

Define Contralateral

Answer 4

• Activity on the left side of the body is controlled by the right hemisphere and vice versa.
• Including both motor and sensory pathways!!!

Question 5

Define the cerebral cortex

Answer 5

• The outer layer of both hemispheres is called the cerebral cortex.
• It is a 3 mm layer covering the inner parts of the brain.

Question 6

What are the 6 areas/ cortex’s in the brain?

Answer 6

1) Motor cortex
2) Auditory cortex
3) Visual cortex
4) Somatosensory cortex
5) Broca’s area
6) Wernicke’s area

Question 7

1. Motor cortex

Answer 7

Location: Parietal lobe.
- Contralateral.
- Involved in the planning, control and execution of voluntary muscle movements.
- Works with other areas of the brain and the spinal cord to translate thoughts into physical motion.

Question 8

2. Auditory cortex

Answer 8

Location: both hemispheres (top of temporal lobe).
- Receives and processes sound information from the ears.
- Damage: deafness.

Question 9

3. Visual cortex

Answer 9

Location: Occipital lobe.
- Visual processing centre.
- Each hemispheres occipital lobe receives info from the contralateral visual field.
- Damage: blindness (partial/ full).

Question 10

4. Somatosensory cortex

Answer 10

Location: Parietal lobe.
- Contralateral.
- Detects various stimuli (e.g. touch and temperature).
- Processes feelings like pain etc.
- Damage: loss of sensation, agnosia, neglect.

Question 11

5. Broca’s area

Answer 11

Location: bottom of frontal lobe.
- Responsible for speech production.
- Damage: Broca’s aphasia.

Question 12

6. Wernicke’s area

Answer 12

Location: top of temporal lobe (left hemisphere).
- Responsible for speech comprehension.
- Essential for understanding spoken and written language.
- Damage: Wernicke’s aphasia.

Question 13

Research against localisation of function (Lashley’s rats)- Method

Answer 13

• Trained a rat to go through a maze without mistakes in search of food.
• Then he removed part of its cortex and observed what effect this would have on its memory and ability to solve the maze.
• He removed 10-50% of the cortex on different trials.

Question 14

Lashley rats- results.

Answer 14

• Memory of the maze depended on the percentage of cortex destroyed but not on the location of where it was destroyed.
• Supports Lashley’s theory of equipotentiality.

Question 15

Evidence to support Localisation of function (Phineas Gage)

Answer 15

• Iron rod through his frontal lobe.
• Led to his personality changing from a capable and efficient foreman (strong work ethic, drive etc.), to angry and impatient, unpredictable= child-like mental capacity.
• He was unable to process emotions or control impulsive behaviour.
• Suggests that the frontal lobe regulates personality.